From a safety point of view I'd be looking for IP44 plugs and sockets, how far is the run ??. I help out with a scout group fireworks display and with 2.5mm arctic flex and IP44 splitters we seem to be able run lights a good distance away. (RCD protected of course)

Is there a simplier and safer alternative which won't cost a fortune for the church?

Used properly with appropriate IP rated connections there shouldn't be any safety issues with using extension leads - I'm struggling to think of anything that would be 'simplier' or more cost effective for this temporary installation!

Extension leads are pretty normal for this kind of thing, just make sure that no one can trip over them. There isn't really any other way unless you do this every week in the same place! There really is nothing wrong with flexible cables, and you can always use H07-RN if there is significant danger of mechanical damage which in this environment there probably isn't.

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DavidOne time "wiring monkey" but not any more!

I was asked to cast an eye over just such a setup last December - as usual the point of the exercise was to raise money for good causes, rather than spend it on electrical equipment, so my preferred solution wasn't even in the running so it was just a case of making the best of the the umpteen daisy-chained extensions. A careful inspection, a plug-in RCD and a plug-in energy monitor later and I was happy. Most of the tree lights were LED and took surprisingly little current and although not all the trees were lit, pretty much the whole lot ran quite comfortably off a single 13A socket.

We used to have a church group use the students union when I worked there as a lighting rigging tech. They used to daisy chain 4/6way 13amp extentions, on of the end of the other, with 40w pendants off each one, hanging over the balcony of the main room to create 'mood light' within the area below.

One string of extensions lights going one way, another there way, out of each half of a double socket.

Looks horrable, but if you do the sums you can have an hell of a lot of 40w bulbs off a 13amp plug before there are any issues, so happy days.